PROBLEM TO BE SOLVED: To provide a prevention and/or a therapeutic composition of involuntary movement, particularly to provide a prevention and/or a therapeutic composition of dystonia.SOLUTION: It is confirmed that tardive dystonia can be improved by administering pramipexole hydrochloride hydrate which is a dopamine D2/D3 receptor agonist to patients developing tardive dystonia which causes involuntary movement, and thereby the prevention and/or the therapeutic composition (particularly, the prevention and/or the therapeutic composition of dystonia) of involuntary movement of the invention is completed.